The effectiveness of booster seat laws for reducing deaths, especially for 6- and 7-year-olds, is clearly shown in a new study by researchers at Boston Children’s Hospital. The researchers analyzed all crashes in the Fatality Analysis Reporting System that involved children ages 4 through 7 that took place between 1999 (when the first booster laws went into effect) and the end of 2009. In that period, 47 states and the District of Columbia passed booster seat laws. The researchers sought to control for factors that had not been taken into account in previous studies.

Because not all state laws covered the full range of children, the cases were separated into two age groups: 4 to 5 and 6 to 7. The child death rates were analyzed by state while taking into account the year in which each state’s booster law took effect and a variety of other factors, such as state highway speed limit, legal blood alcohol limit, adult fatality rates, and median household income. The level of enforcement of the states’ booster laws could not be factored in, however.

The study showed that, nationally, the implementation of state booster laws made the chance of death 11 percent less likely for 4- and 5-year-olds, 22 percent less likely for 6-year-olds, and 25 percent less likely for 7-year-olds.